Ink jet printing systems are known in which a print head defines one or more rows of orifices which receive an electrically conductive recording fluid, such as for instance a water based ink, from a pressurized fluid supply manifold and eject the fluid in rows of parallel streams. Printers using such print heads accomplish graphic reproduction by selectively charging and deflecting the drops in each of the streams and depositing at least some of the drops on a print receiving medium, while others of the drops strike a drop catcher device.
In certain printing systems, particularly ink jet printing systems, the amount of ink or other colorant applied to the substrate must be limited. In the case of high speed ink jet printing systems, using water based dye inks, ink limiting is of particular concern to avoid degradation of the substrate. Excessive water causes the paper to stretch and wrinkle. This problem is amplified by web tensioning in high speed roll to roll systems. A careful balance between ink loading, print speed, web tension, and drying power, must be maintained. This invention solves two related problems. It identifies the upper ink limit for the above mentioned parameters. Secondly, it linearizes the tone scale of each ink in the system from the substrate color to the maximum ink limit. In the past, the dependency between ink and substrate has not been as pronounced. High speed ink jet systems that add a lot of water to the paper in a short period of time have compounded this problem.
In the prior art, upper ink limits for a few selected substrates were predefined by printer manufacturers. High speed digital presses will be operated with a number of substrates of unknown ink compatibility. In addition, the color of these unprinted substrates may vary significantly. Also, the color of ink available in the system may change on a regular basis.
It is seen, therefore, that it would be desirable to have a technique for solving the problem of universal calibration procedures for any set of inks, substrates, and machine configurations.